American philanthropist, born at Hampden, Maine, on the 4th of April 1802. Her parents were poor and shiftless, and at an early age she was taken into the home in Boston of her grandmother, Dorothea Lynde, wife of Dr. Elijah Dix. Here she was reared in a distinctly Puritanical atmosphere. About 1821 she opened a school in Boston, which was patronized by the well-to-do families; and soon afterwards she also began teaching poor and neglected children at home. But her health broke down, and from 1824 to 1830 she was chiefly occupied with the writing of books of devotion and stories for children. Her Conversations on Common Things (1824) had reached its sixtieth edition by 1869. In 1831 she established in Boston a model school for girls, and conducted this successfully until 1836, when her health again failed.

In 1841 she became interested in the condition of jails and almshouses, and spent two years in visiting every such institution in Massachusetts, investigating especially the treatment of the insane poor. Her memorial to the state legislature dealing with the abuses she discovered resulted in more adequate provision being made for the care and treatment of the insane, and she then extended her work into many other states. By 1847 she had travelled from Nova Scotia to the Gulf of Mexico, and had visited 18 state penitentiaries, 300 county jails and houses of correction, and over 500 almshouses. Her labors resulted in the establishment of insane asylums in twenty states and in Nova Scotia and Newfoundland, and in the founding of many additional jails and almshouses conducted on a reformed plan.

In 1854 she secured the passage by Congress of a bill granting to the states 12,250,000 acres of public lands, to be utilized for the benefit of the insane, deaf, dumb and blind; but the measure was vetoed by President Franklin Pierce. After this disappointment she went to England for rest, but at once became interested in the condition of the insane in Scotland, and her report to the home secretary opened the way for sweeping reforms. She extended her work into the Channel Islands, and then to France, Italy, Austria, Greece, Turkey, Russia, Sweden, Norway, Denmark, Holland, Belgium and a part of Germany. Her influence over Arinori Mori, the Japanese chargé d'affaires at Washington, led eventually to the establishment of two asylums for the insane in Japan.

At the outbreak of the American Civil War she offered her services to the Federal government and was appointed superintendent of women nurses. In this capacity she served throughout the war, without a day's furlough; and her labors on behalf of the insane and the infirm were continued after the war. After a lingering illness of six years she died at Trenton, New Jersey, on the 17th of July 1887.